The floor
Confirm the load the machine imposes and that your floor takes it, the space needed including the room to work around the machine for maintenance, and access from the delivery point — doorway heights and turning space, not just the final position. Measure the route, not only the destination.
Power, air and water
Supply voltage, phase and frequency confirmed against the machine's requirement, not assumed. Protection and cabling sized to the machine's actual load. Compressed air at the required pressure and quality — supply is usually available; the required quality and drying often are not. Water and drainage where the process needs them.
Environment and services
Temperature and humidity, which matter to the process as much as to the machine. Extraction and waste handling. Lighting at the machine, not only overhead. Where the machine will be serviced from, and whether the lifting equipment needed for maintenance can actually reach it.
People and documents
Who will operate it and whether they are available on commissioning day — handover to nobody is a wasted visit. The machine documentation, or a photograph of the nameplate if you do not have it. And the spare parts you will want in your store from day one, which is far easier to decide during commissioning than six months later.